I have iOS application(written on objective c) which works with events from the calendar. Something strange that I saw is on change of recurrent meeting is that in the most of the cases the calendarItemExternalIdentifier field was changed and there is /RID=XXXXXXX part is added but in some of the cases I receive same calendarItemExternalIdentifier with 20161205 added at the end.
For example I have external identifiers like this:
oiok2qp12o6k3d2ru34v885njo@google.com
And on change I can receive this:
oiok2qp12o6k3d2ru34v885njo@google.com/RID=505299600
or this:
oiok2qp12o6k3d2ru34v885njo@google.com<!ExceptionDate!>20161205
Why we have this and what is the difference?
As far as I figured out (while on search for an answer for this, too)< the difference relies on which calendar type you are using.
Exchange Calendar events use /RID=, where the Timestamp is the time interval since 00:00:00 UTC on 1 January 2001 to the new Date.
while
Local Calendar (and I think CalDAV Calendars - I'll check this later) use